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SubjectRe: [PATCH 1/2] vfio/mtty: Fix eventfd leak
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On 10/13/23 21:56, Alex Williamson wrote:
> Found via kmemleak, eventfd context is leaked if not explicitly torn
> down by userspace. Clear pointers to track released contexts. Also
> remove unused irq_fd field in mtty structure, set but never used.

This could be 2 different patches, one cleanup and one fix.

> Fixes: 9d1a546c53b4 ("docs: Sample driver to demonstrate how to use Mediated device framework.")
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
> samples/vfio-mdev/mtty.c | 28 +++++++++++++++++++++++-----
> 1 file changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> index 5af00387c519..0a2760818e46 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -127,7 +127,6 @@ struct serial_port {
> /* State of each mdev device */
> struct mdev_state {
> struct vfio_device vdev;
> - int irq_fd;
> struct eventfd_ctx *intx_evtfd;
> struct eventfd_ctx *msi_evtfd;
> int irq_index;
> @@ -938,8 +937,10 @@ static int mtty_set_irqs(struct mdev_state *mdev_state, uint32_t flags,
> {
> if (flags & VFIO_IRQ_SET_DATA_NONE) {
> pr_info("%s: disable INTx\n", __func__);
> - if (mdev_state->intx_evtfd)
> + if (mdev_state->intx_evtfd) {
> eventfd_ctx_put(mdev_state->intx_evtfd);
> + mdev_state->intx_evtfd = NULL;
> + }
> break;
> }
>
> @@ -955,7 +956,6 @@ static int mtty_set_irqs(struct mdev_state *mdev_state, uint32_t flags,
> break;
> }

Shouln't mdev_state->intx_evtfd value be tested before calling
eventfd_ctx() ?

Thanks,

C.


> mdev_state->intx_evtfd = evt;
> - mdev_state->irq_fd = fd;
> mdev_state->irq_index = index;
> break;
> }
> @@ -971,8 +971,10 @@ static int mtty_set_irqs(struct mdev_state *mdev_state, uint32_t flags,
> break;
> case VFIO_IRQ_SET_ACTION_TRIGGER:
> if (flags & VFIO_IRQ_SET_DATA_NONE) {
> - if (mdev_state->msi_evtfd)
> + if (mdev_state->msi_evtfd) {
> eventfd_ctx_put(mdev_state->msi_evtfd);
> + mdev_state->msi_evtfd = NULL;
> + }
> pr_info("%s: disable MSI\n", __func__);
> mdev_state->irq_index = VFIO_PCI_INTX_IRQ_INDEX;
> break;
> @@ -993,7 +995,6 @@ static int mtty_set_irqs(struct mdev_state *mdev_state, uint32_t flags,
> break;
> }
> mdev_state->msi_evtfd = evt;
> - mdev_state->irq_fd = fd;
> mdev_state->irq_index = index;
> }
> break;
> @@ -1262,6 +1263,22 @@ static unsigned int mtty_get_available(struct mdev_type *mtype)
> return atomic_read(&mdev_avail_ports) / type->nr_ports;
> }
>
> +static void mtty_close(struct vfio_device *vdev)
> +{
> + struct mdev_state *mdev_state =
> + container_of(vdev, struct mdev_state, vdev);
> +
> + if (mdev_state->intx_evtfd) {
> + eventfd_ctx_put(mdev_state->intx_evtfd);
> + mdev_state->intx_evtfd = NULL;
> + }
> + if (mdev_state->msi_evtfd) {
> + eventfd_ctx_put(mdev_state->msi_evtfd);
> + mdev_state->msi_evtfd = NULL;
> + }
> + mdev_state->irq_index = -1;
> +}
> +
> static const struct vfio_device_ops mtty_dev_ops = {
> .name = "vfio-mtty",
> .init = mtty_init_dev,
> @@ -1273,6 +1290,7 @@ static const struct vfio_device_ops mtty_dev_ops = {
> .unbind_iommufd = vfio_iommufd_emulated_unbind,
> .attach_ioas = vfio_iommufd_emulated_attach_ioas,
> .detach_ioas = vfio_iommufd_emulated_detach_ioas,
> + .close_device = mtty_close,
> };
>
> static struct mdev_driver mtty_driver = {

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